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Fixed gas detectors

A fixed gas detector is a gas sensor used to monitor concentrations. There are different types of gas transmitters like combustible gas transmitters (natural gas, LGP, hydrocarbons, solvents, alcohols), toxic gas monitoring systems, VOC meters (volatile organic compounds), asphyxiant gas or refrigerant monitoring systems (for freons).

Fixed gas detector or gas transmitter in complete fixed gas detection systems

Most of fixed gas detection systems for toxic and combustible gases feature a 4-20 mA linear output to connect to a gas detection controller and are ATEX compliant. A more advanced fixed gas detector can also be equipped with a digital display, alarm relays or digital communication. There is a specific sensor technology for each type of gas that ensures the accuracy and the frequency of measurements… (Learn more about sensor technologies).


    A combustible gas detector (natural gas, LPG, hydrocarbons, solvents, alcohols) stands for the largest part of gas detection. A fixed gas detector for combustible gas can be used in almost any sector: industries with SEVESO  or COMAH sites, chemistry, petro chemistry and also in the tertiary sector with boiler rooms gas detection for example. There are two major monitoring technologies depending on the targeted combustible gas to detect :

    . Catalytic sensors: sensor technology used for almost every combustible gas. This solution is very efficient for natural gas, LPG, hydrocarbons, solvents and even some volatile compounds monitoring.

    . Infrared sensors: this technology should be preferred for every sector with a constant residual presence of combustible gases (refineries, paint or solvents plants, distilleries…).


    As the use and the manufacturing of highly toxic products in the industry is growing stronger, dangers to goods (risk of explosion) and to people (risk of poisoning) are growing as well. Throughout the world every day explosions and death occur and recall this problem.

    The most commonly used sensor technology for monitoring toxic gases is the electrochemical sensor. This technology, that can be found in a portable or a fixed gas detector, provides a large panel of gas detection sensors. For some rare gases that require measurements expressed in ppb (parts per billion), only the colorimetric paper technology will be available for fixed gas detection.


    Asphyxiating gases includes many gases with the same property: they reduce oxygen rate. Even if in almost any case an oxygen gas detector (O2 detector) is enough, it is recommended to use an asphyxiant gas detector when it is available such as a CO2 gas detector (carbon dioxide) or an helium fixed gas detector for example.

    . Electrochemical sensor for oxygen and some rare gases

    . Infrared absorption sensor for carbon dioxide (CO2)

    . Catalytic sensor for almost any combustible gas that can replace oxygen in case of leakage


    Volatile organic compounds (VOC) are a wide family of gases and gaseous substances that can be pollutant, toxic and even carcinogenic. As they are volatile, they can easily spread into the atmosphere. That’s why it is necessary to detect and measure them with a fixed VOC monitor to be protected.

    Even if VOC can compose explosive mixtures, they are very toxic before their concentrations reach an explosive level (tens of thousands parts per million). Indeed, their level of explosiveness is set at tens of ppm. Several technologies for VOC detectors are available depending on the risk to monitor:

    . Photo-ionization lamp (PID lamp) or semi-conductor sensor for toxicity detection (expressed in ppm).

    . Catalytic sensor or infrared absorption sensor (when available) for explosiveness detection (expressed in % LEL).


    Halogenated hydrocarbons (CFCs and HCFCs), alkenes (HFOs) and almost any refrigerant gas are regulated under a particular legislation that limits (or forbids) their use. The use if refrigerants also requires a monitoring system – usually a fixed gas detector for freons. There are two main measuring technologies for freons:

    . Semi-conductor sensors: the most commonly used technology for freons monitoring

    . Infrared absorption sensors: a very accurate but very expensive technology used for some freons

GazDetect offers, on specific territories, many services for fixed gas detection like on-site installation, setup, commissioning and calibration of gas detectors. We can also perform maintenance and periodical checkings of your fixed systems. (go to the Maintenance and on-site calibration section)

Our fixed gas detector range :

The OBSERVER-i is the world’s first ultrasonic gas leak detector equipped with Artificial Neural Network (ANN) real-time broadband acoustic sound processing technology. This technology is based on extensive studies and real recording of gas leak sounds and industrial background noise from a wide array of industry sources over the years.

  • détecteur de gaz à ultrasons observer-i
  • Quickly detects leaks of all gases from 2 bar (hydrocarbons, hydrogen, ammonia, etc.)
  • Wide detection range while maintaining immunity to false alarms
  • Uniform detection coverage in noisy and low-noise areas
  • Patented and proven Senssonic™ self-test function
  • Frequency range up to 12Hz without background noise
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The KwikSense is a digital gas transmitter ATEX dedicated to the detection of flammable gases, toxic gases, and volatile organic compounds. It has a digital display, 4-20mA and MODBUS outputs, and alarm relays for the detection of the gases Br2, C2H2, C2H3Cl, C2H6O, C3H8, C4H10O, C6H6, CH3OH, CH3SH, CH4, CH2O, Cl2, CO, CO2, COCl2, CS2, ETO, GPL, H2, H2O2, H2S, HCl, HC, HCN, HF, NH3, NO2, O2, O3, PCl3, PH3, POCl3, SO2 & COV.

  • Transmetteur gaz numérique KwikSense
  • Digital gas transmitter ATEX for the detection of explosive, toxic and asphyxiating gases, and VOC
  • Digital display and three-color LEDs to indicate detector status
  • Rugged, explosion-proof housing with cast aluminium alloy
  • 4-20mA, MODBUS, and 1 or 3 relay outputs depending on model
  • Excellent value for money with many accessories available
Icon of EN-KwikSense-Web EN-KwikSense-Web (226.7 KiB)
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The KwikSense PID VOC detector, ATEX certified, is dedicated to the volatile organic compounds detection. It is an ATEX transmitter with linear 4-20 mA output, alarm relay, and a digital display that can be connected to a control system (safety PLC, gas detection system) or used as a stand-alone control point.

  • Fixed VOC detector KwikSense PID
  • VOC detectors with PID technology (10.6 eV photo-ionization lamp) for the detection of volatile organic compounds
  • Digital display and three-colored LEDs to indicate the status of the detector (alarms, faults, etc.)
  • Rugged, explosion-proof housing with cast aluminium alloy
  • 4-20 mA, MODBUS, and 1 or 3 relay outputs depending on the model
  • Numerous compatible accessories: calibration cap, gas manifold, climate protection, duct mounting kit

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The NS II fixed detector is dedicated to monitoring gas concentrations in classified areas (ATEX zone 2).

Detection : organic acids, Alcohol, Br2, C2H2, C2H4, C2H4O, C2H5OH, C2H6, C3H6, C4H10, C5H12, CH2O, CH4, Cl2, ClO2, CO, CO2, COV, H2, H2O2, H2S, HBr, HCl, HCN, HF, Hydrocarbons, N2O, NH3, NO, NO2, O2, O3, PH3, R1234yf, R401A, R404A, R407C, R32, R410A, R12, R22, SiH4, SO2.

  • NS III ATEX zone 1 SIL 2 fixed gas detector
  • Wide range of detected gases (88 sensors)
  • ATEX zone 2 certification
  • 4-20 mA & RS485 (DEGA protocol) outputs as standard
  • Available options: 3 relay card, 88 dBA buzzer, Modbus output
  • Internal data recording (last 30 days)

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The NB III transmitter is dedicated to gas detection in safe areas (not ATEX).

Detection: organic acids, Alcohol, Br, C2H2, C2H4, C2H4O, C2H5OH, C2H6, C3H6, C4H10, C5H12, CH2O, CH4, Cl2, ClO2, CO, CO2, COV, H2, H2O2, H2S, HBr, HCl, HCN, HF, Hydrocarbons, N2O, NH3, NO, NO2, O2, O3, PH3, R1234yf, R401A, R404A, R407C, R32, R410A, R12, R22, SiH4, SO2.

  • Fixed gas transmitter NB III for safe zones
  • 88 pre-calibrated and interchangeable sensors
  • Analog (4-20 mA) and RS485 (DEGA protocol) outputs as standard
  • Available with or without display
  • Data logging
  • Available options: 3 relay card, Modbus card
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The iTrans2 fixed gas detector features high technology and multiple options, such as having two detectors attached to one head. The iTrans2 is ideal for industrial sites as it identifies explosive, toxic, and asphyxiating gases. It is easy to use and has a low installation cost.

  • Détecteur de gaz fixe iTrans2
  • Non-intrusive calibration
  • Intelligent sensors
  • MODBUS or HART communication protocol
  • Programmable relays
  • Up to 2 detection points on one head
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The MGS-450 CO2 controller can be used as a standalone carbon dioxide detector or can be connected to the MGS-408 multi-point controller.

  • CO2 controller MGS-450 carbon dioxide standalone detector
  • IP66 autonomous CO2 detector
  • Infrared sensor, measures 0-5000 ppm or 0-5% / vol.
  • Integrated buzzer (72 dB) & relays for servo controls
  • Simplified commissioning and maintenance via the MGS-400 mobile application
  • Outputs: 4-20 mA, Modbus RTU, 3 configurable SPDT relays
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4-20 mA output B12 ATI gas transmitter with or without display for gas detection: Alcool, AsH3, B2H6, Br2, C2H2, C2H4O, CH2O, Cl2, ClO2, CO, COCl2, F2, GeH4, H2, H2O2, H2S, H2Se, HCl, HCN, HF, I2, NH3, NO, NO2, Nox, O2, O3, PH3, SiH4, SO2 & organic vapors.

  • ATI B12 gas transmitter
  • Fixed gas transmitter with 4-20 mA linear output
  • NEMA 4X polystyrene enclosure
  • Fast response time
  • Low power consumption, 12-28 VDC
  • Available with or without display
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The Oldham CTX300 gas detector is a fixed analog transmitter with a 4-20mA output, and a very wide range of sensors for monitoring toxic gases, asphyxiants, solvents and refrigerants.

Fixed detector : C2H4O, Cl2, ClO2, CO, CO2, COCl2, H2S, HCl, HCN, He, HF, NH3, NO, NO2, O2, O3, PH3, SiH4, SO2, organic vapors (VOC) & freons (CFC, HFC, HFO)

  • Oldham CTX 300 fixed gas detector
  • Interchangeable pre-calibrated sensors
  • Optional backlit digital display
  • Insensitivity to corrosive agents
  • Power supply 15 to 32 VDC
  • Safe area certification
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The Honeywell SensePoint fixed gas detector monitors toxic, explosive and oxygen gas concentrations in ATEX zones.

Detection: EXPLO LEL, NH3, Cl2, NO2, SO2, H2, H2S, CO, O2

  • SensePoint Honeywell fixed gas detector
  • Oxygen detector, explosive or toxic gas
  • Excellent value
  • Four-way connection box
  • ATEX certified, IP65
  • Quick and easy installation
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The Polytron 3000 detector is a Dräger fixed gas detector dedicated to monitoring toxic gas and oxygen concentrations.

Detection : NH3, AsH3, HBr, C4H6, Cl2, BCl3, HCN, B2H6, NO2, SO2, C3H5ClO, C2H4, CH2O, N2H4, H2, C3H8O, CH4O, C5H8O2, NO, CO, C3H6O, OV, O2, O3, PH3, C3H6, SiH4, C8H8, H2S, SiCl4

  • Fixed gas detector Polytron 3000 by Dräger
  • Wide range of detected toxic gases
  • DrägerSensor smart sensor
  • Modular detector
  • Optional display
  • ATEX and SIL2 certification

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The SensePoint XRL gas transmitter is a Bluetooth ATEX detector with display suitable for the most difficult applications.

Detection: EXPLO LEL, NO2, H2, CO, O2, H2S

  • Sensepoint XRL Honeywell fixed gas detector
  • 4-20 mA linear output or Modbus RTU
  • Bluetooth Low Energy technology
  • LM20 aluminum alloy housing
  • Visual indicators
  • ATEX certification
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The Bacharach MGS 450 fixed refrigerant leak detector is a device that can be used as a standalone detector or can be connected to a gas controller. Configuration done via Bluetooth on mobile application. To prevent false alarms, the MGS-450 is equipped with high quality pre-calibrated sensors.

  • Bacharach MGS 450 fixed refrigerant leak detector
  • HFO, HFC, HCFC, NH3 and CO2 monitoring
  • Operating in down to -40 ° C environments
  • Bluetooth connection on the MGS-400 mobile application
  • Operates independently or can connected to a gas controller
  • Three-color LED alarm lights & and audible alarm (72 dB)
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With its infrared technology the GD10P fixed gas detector monitors hydrocarbon vapors and CO2 carbon dioxide. The detector's auto-test function signals defaults on the optical system or malfunction to the controller and requires minimal maintenance.

  • Oldham GD10P Infrared fixed gas detector
  • Fixed gas detector with infrared technology: hydrocarbons vapors and CO monitoring
  • 5 years guarentee – 15 years warranty on the infrared sensor (Simtronics patent)
  • Ongoing auto-test: signals optical defaults or malfunction to the controller
  • No saturation: the detector is able to monitor concentrations up to 100% vol.
  • Factory calibration, no onsite calibration, minimal maintenance
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The Oldham OLCT710 TP is a fixed gas detector dedicated to hydrogen sulfide monitoring. This H2S gas transmitter was especially designed to be efficient in high H2S concentrations and is ideal for use in oil and gas applications, or water & wastewater treatment plant environments

  • Fixed H2S detector with semiconductor gas sensor OLCT710 TP by Oldham
  • Semiconductor gas sensor technology
  • ATEX & SIL2 certification
  • Made for use even in the harshest conditions (-40°C to +75°C)
  • IP66 protection ingress
  • 4-20 mA analog output & RS48 Modbus
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The Bacharach MGS 410 is a fixed refrigerant gas detector to be connected to the Bacharach MGS-408 gas controller unit (8 channels). It is a device capable of monitoring many refrigerant gases and can be connected to a building management system through Modbus. Specially designed for use in this type of environment, the MGS-410 refrigerant gas detector can withstand temperatures ranging from -40 ° C to + 50 ° C.

  • Fixed refrigerant gas detector - Bacharach MGS 410
  • Works in extreme conditions: -40 ° C to + 50 ° C
  • Dedicated MGS-408 controller unit
  • Embedded alarms (audible & visual)
  • Protection: IP66
  • Configuration on the MGS-400 mobile application
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Honeywell's XCD-RFD and XCD-RTD gas transmitters are fixed gas monitors specially designed for use with remotely installed sensors. These gas transmitters can be placed up to 30 meters away from the gas sensor and then allow information on the toxic or flammable gases presence in an area to be consulted before entering it.

  • Up to 30 meters away from the sensor
  • Backlit display
  • Clear color code
  • Compatible with many gas sensors
  • Preconfigured and fully configurable
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The XNX gas transmitter is able to accept all inputs from various Honeywell Analytics gas sensors. It uses standard 4-20mA or HART wiring and works with several communication protocols (Modbus, Fieldbus, etc.). Its backlit multilingual LCD display gives all necessary status information as text, numbers and icons.

  • Honeywell XNX universal gas transmitter
  • Compatible with all local or remote Honeywell Analytics detectors
  • International hazardous area approval
  • Several communication protocols (Hart, Modbus, Fieldbus, etc.)
  • Many input and output options
  • Aluminum alloy or stainless steel case
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The Honeywell SensePoint XCL detector is an ideal gas leak detector for commercial or service environments.

Detection : EXPLO LEL, NH3, NO2, CO2, H2, CO, O2, H2S

  • Sensepoint XCL Honeywell fixed gas detector
  • Outputs: analog or digital, 2 relays (option)
  • Catalytic, electrochemical or infrared sensor
  • Bluetooth connection for configuration and maintenance via smartphone
  • Several colors available
  • Operating from -20 to + 50 °C
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Especially designed for the detection of oxygen, combustible and toxic gases, the Oldham OLCT10N digital fixed gas detector ensures reliable and fast concentration levels monitoring. Every information is sent to the gas detection controller in less than a second.

  • Oldham Fixed gas detector OLCT10N
  • Detection of CH4, O2, CO, H2S, NO, NO2, NH3.
  • Power supply 12-30 V DC.
  • RS485 Modbus digital signal.
  • Immune to dust and water.
  • ATEX 3 GD, ATEX 2 and 22 approved.
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Oldham OLCT10-Freons refrigerant gas leak detector with 4-20 mA linear output for refrigerant application in classified area.

  • Fixed gas detector Oldham OLCT10
  • Detection of R11, R12, R22, R23, R32, R123, R134A, R141B, R143A, R227, R404A, R410A, R407C, R408A, R507, FX56
  • Power supply: 15 to 30 VDC – 4-20 mA linear output
  • Robust, compact and easy to use
  • Approval: ATEX II 3 G / EEx nA IIC T4 – Electromagnetic compatibility according to EN-50270
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Especially designed for use in boiler rooms or parkings, the Oldham OLCT10 sensor range is used to monitor presence of explosive vapors and gases or combustion toxic gases in ambient air.


  • Fixed gas detector OLCT10 by Oldham
  • Detection of the combustible gases, CO, NO, NO2
  • Power supply: 15 to 30 VDC
  • 4-20 mA linear output
  • Robust, user-friendly and easy to install
  • ATEX II 3 G / EEx nA IIC T4 approved
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SIL 2 approved ATEX gas detector to detect the combustible gases (IR or catalytic), CO2 (IR), toxic gases (electrochemical), solvents or freons (semiconductor) and asphyxiating gases (oxygen deficiency).

  • Fixed gas detector OLCT100
  • Detection of hydrocarbons, solvents, toxic gases, freons, VOC, CO2
  • Housing made of aluminium with epoxy paint (optional 316L Stainless Steel version)
  • Outputs: OLC100: Wheatstone bridge – OLCT100: 4-20 mA linear
  • Power supply: 15.5 to 32 VDC
  • ATEX & SIL 2 approved for catalytic and infrared versions
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Loop-powered (4-20 mA 2 wires) and equipped with an LCD display, the Serie 3000 fixed oxygen and toxic gas detector is particularly well-suited for potentially explosive atmospheres (ATEX zones).

  • Fixed gas detector serie 3000 transmitter
  • Large range of pre-calibrated gas detection sensors
  • Loop-powered, 2 cables
  • LCD screen for setup and concentrations display
  • Aluminum version or stainless steel with epoxy paint version
  • Approved for hazardous areas, L/c-UL, ATEX, IECEx. Protection IP66 (EN 60529), NEMA 4X
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ATEX gas detector with 4-20 mA linear output, display, 3 relays (alarm 1, alarm 2 and fault) and MODBUS communication. Detection of the combustible gases (IR or catalytic), CO2 (IR) or toxic gases (electrochemical).

  • Fixed gas detector XCD
  • Detection of combustible gases, CO, CO2, CH4, H2, H2S, O2
  • Power supply: 15.5 to 32 VDC with 4-20 mA relay output
  • Aluminium or IP 65 stainless steel housing
  • Approval: ATEX II 2G EExd ia d IIC T4
  • Integrated mounting plate with 3 mounting holes – 2 M20 cable gland entries
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4-20 mA detector/transmitter with relay outputs and RS485 communication. Pre-calibrated sensors to detect oxygen, flammable and toxic gases.

  • Fixed gas detector Oldham OLCT80
  • Detection of O2, CO, CO/H2 NUL, H2S, NO, NO2, SO2, Cl2, H2, HCl, HCN, HF, NH3, ETO, O3, PH3, ClO2, SiH4, COCl2, AsH3, CH4, H2, NH3, VOC
  • Alarms: 2 gas alarms (alarm 1, alarm 2) and 1 fault alarm
  • Inputs and outputs: 4-20 mA with signal smart treatment
  • Approval: ATEX – II 2 GD, INERIS 03ATEX0240X, compliance with EN50270 standard, IP66
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The Satellite XT is a fixed gas detector with interchangeable sensors. It is especially designed to continuously monitor hazardous concentrations of gases.

Detected gases: AsH3, BBr3, B2H6, BCl3, BF3, Br2, C2H4O, Cl2, ClF3, ClO2, CO, COCl2, F2, GeH4, H2, H2S, H2Se, HBr, HCl, HCN, HF, HMDS, MCF, MMH, N2H4, NH3, NO, NO2, O2, O3, PH3, POCl3, SiCl4, SiHCl3, SO2,TBA, TBP, TDMAT, TEOS, TMB, TMP, UDMH, WF6.

  • Fixed gas detector Satellite XT
  • Pyrolysis module detection: C4F6, C5F8, CH3F, DCE 1.2, NF3, SF6
  • Pre-calibrated interchangeable sensors, easy maintenance
  • 4-20mA linear output
  • 3 optional single-pole relays
  • Optional remote measure (up to 3 meters)
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4-20 mA gas detector / transmitter with integrated sampling pump, pre-calibrated cartridge, alarm relays and TCP/IP communication.

Detection of AsH3, B2H6, BCl3, BF3, Br2, C2H4O, Cl2, ClF3, ClO2, CO, COCl2, F2, GeH4, H2, H2S, H2Se, HBr, HCl, HCN, HF, HMDS, N2H4, NH3, NO, NO2, O2, O3, PH3, POCl3, Si2H6, SiCl4, SiHCl3, SO2, TEOS, TMB, TMP, WF6

  • Fixed gas detector Midas
  • Detection with pyrolysis module of C4F6, C5H8, CH3F, DCE 1.2, NF3, SF6
  • Integrated aspirated pump: 500 mL/min flow
  • 3 configurable NO or NF alarm relays
  • High accuracy measurement from ppb to ppm
  • Ethernet (PoE) TCP/IP and Modbus communication
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The Honeywell Analytics SPM Flex is an optical calibration-free gas optical analysis system. This single point tape-based toxic gas detector can accurately (ppb measurement) and swiftly monitor the presence of a hazardous gas.

  • Honeywell SPM Flex gas monitor with optical toxic gas analysis
  • Chemcassette® technology – immune to interferences, more than 50 available gases.
  • Calibration-free, minimal maintenance .
  • Audiovisual alarm (2 thresholds).
  • User-friendly interface and gas concentration digital display.
  • UL 61010-1 / CSA-C22.2 / IEC 61010-1 certified
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Infrared (IR) combustible gas and hydrocarbon detector with 4-20 mA output. ATEX and SIL 2 (EN 50402) approved with many factory configured calibration curbs.

  • Fixed gas detector Optima +
  • Detection of the combustible gases
  • More than 40 specific gas curbs available factory calibrated
  • 4 ray dual source infrared IR technology
  • Very fast response time (T90 < 8 seconds)
  • Very high reliability (MTBF > 28 years)
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B12 2 wire transmitter with 4-20 mA output for use in environments with up to 100% relative humidity.

  • Fixed gas detector B12
  • Power supply: from 12 to 28 VDC – low consumption
  • Measuring range: 0-10/100 ppm or 0-200/2,000 ppm
  • Corrosion-resistant sensor
  • Direct real-time measure of H2O2 concentration
  • Operating temperature: between 0 and 50°C
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